Precise power control in wireless communication systems such as cellular mobile telephone systems can be problematic, especially at the edge of a cell where interference is often the highest. Due to potential interference, the benefit of techniques such as high order modulation to transmit at higher data rates can be limited.
Code Division Multiple Access (CDMA) systems such as 20 IS-95 and IS-2000 are interference limited, and their inherent capacity generally can be enhanced using beam-steering techniques. For example, based on indoor and outdoor field trials, significant improvements in signal to interference ratio (SIR) has been achieved using directional antenna arrays.